Calculating electrical power when the voltage and current are known is a fundamental task in electrical engineering and everyday applications. The relationship between these quantities is given by a simple formula.
The Formula: \( P = V \cdot I \)
The formula to find electrical power is:
\[ P = V \cdot I \]
Where:
- \( P \) is the power (measured in watts, W)
- \( V \) is the voltage (measured in volts, V)
- \( I \) is the current (measured in amperes, A)
Example 1: Power Consumption of a Light Bulb
Question: A light bulb operates at 120 volts and draws a current of 0.5 amperes. What is the power consumption of the light bulb?
Calculation:
Given:
- \( V = 120 \) V
- \( I = 0.5 \) A
Using the formula:
\[ P = V \cdot I = 120 \cdot 0.5 = 60 \, \text{W} \]
Result: The power consumption of the light bulb is 60 watts.
Example 2: Power of an Electric Heater
Question: An electric heater runs on 240 volts and has a current of 10 amperes. What is the power output of the heater?
Calculation:
Given:
- \( V = 240 \) V
- \( I = 10 \) A
Using the formula:
\[ P = V \cdot I = 240 \cdot 10 = 2400 \, \text{W} \]
Result: The power output of the electric heater is 2400 watts.
Example 3: Power Supply for a Laptop
Question: A laptop power supply provides 19 volts and 3.42 amperes. What is the power supplied to the laptop?
Calculation:
Given:
- \( V = 19 \) V
- \( I = 3.42 \) A
Using the formula:
\[ P = V \cdot I = 19 \cdot 3.42 = 64.98 \, \text{W} \]
Result: The power supplied to the laptop is approximately 65 watts.
